Method for designing reactor protection system for individual state signals

Abstract

The present invention relates to a method for designing a reactor protection system for individual state signals. The reactor protection system receives an input of the individual state signals, determines an operation condition of a reactor shutdown or a safety device, and has a basic number of channels for the input and the determination. The method comprises the steps of: designing the number of channels according to whether to apply at least one from among a malfunction consideration requirement, a single failure requirement, and an online maintenance requirement; designing the multiplexing of the channels according to whether to apply a reliability improvement requirement; and designing the application of a heterogeneous device to the channels according to whether to apply an inherent diversity implementation requirement.

Description

Design method of reactor protection system for individual status signals

[0001] The present invention relates to a design method of a nuclear reactor protection system for individual status signals.

[0002] Nuclear power plants have a protection system that receives various status signals such as temperature, pressure, flow rate, and state change rate, detects abnormal conditions, and determines whether to shut down the reactor or operate engineering safety equipment.

[0003] Recently, the introduction of digital equipment and the demands of various requirements have made the proper design of protection systems very important.

[0004] Therefore, the purpose of the present invention is to provide a design method of a nuclear reactor protection system for individual status signals.

[0005] The above object of the present invention is achieved by a design method of a nuclear reactor protection system for an individual status signal, wherein the nuclear reactor protection system receives the individual status signal and determines a condition for a reactor shutdown or an operating condition of a safety device, the nuclear reactor protection system has a basic number of channels for the input and determination, and includes a step of designing the number of channels depending on whether at least one of a malfunction consideration requirement, a single failure requirement, and an online maintenance requirement is applied; a step of designing multiplexing of the channels depending on whether a reliability improvement requirement is applied; and a step of designing application of heterogeneous devices to the channels depending on whether a self-diversity implementation requirement is applied.

[0006] The above basic number is 1, and each channel includes comparison logic and simultaneous logic. In the step of designing the number of channels, if a malfunction consideration requirement is applied, the number of channels can be increased, if a single failure requirement is applied, the number of channels can be increased, and if an online maintenance requirement is applied, the number of channels can be increased.

[0007] The increase in the number of channels due to the application of the above malfunction consideration requirements, single failure requirements and online maintenance requirements can be performed independently of each other.

[0008] The number of channels may be increased by one each by applying the above malfunction consideration requirements, single failure requirements and online maintenance requirements.

[0009] Multiplexing of the above channels can be performed within individual channels.

[0010] The application of the above heterogeneous devices is applied in a state where individual channels are multiplexed, and can be applied to at least one of between channels and within channels.

[0011] A step of adjusting the number of channels depending on whether a requirement for reducing the number of channels is applied is further included, while all of the malfunction consideration requirements, single-fault requirements, online maintenance requirements, reliability improvement requirements, and self-diversity implementation requirements are applied, and the adjustment of the number of channels can be performed when the single-fault requirement is satisfied by a channel of another type when a channel of one type is bypassed.

[0012] If the above channel number reduction requirement is applied, the number of channels can be reduced from 4 to 3.

[0013] After adjusting the number of channels, a step of determining the number of types of heterogeneous devices may be further included depending on whether the requirement for minimizing the types of heterogeneous devices is applied.

[0014] If the above requirement for minimizing the types of heterogeneous devices is applied, the number of types of heterogeneous devices can be two.

[0015] According to the present invention, a design method of a nuclear reactor protection system for individual status signals is provided.

[0016] FIG. 1 is a part of a flowchart showing a design method of a nuclear reactor protection system according to an embodiment of the present invention.

[0017] Figure 2 is a flowchart of a design method of a nuclear reactor protection system according to an embodiment of the present invention when malfunction is not considered.

[0018] Figures 3a to 3g show the design results of each reactor protection system shown in Figure 2.

[0019] Figure 4 is a flowchart of a design method of a nuclear reactor protection system according to an embodiment of the present invention, in which malfunction is taken into consideration.

[0020] Figures 5a to 5g illustrate the design results of each reactor protection system shown in Figure 4.

[0021] Hereinafter, various embodiments of the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the invention. The present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0022] In order to clearly explain the present invention, parts that are not related to the description are omitted, and the same reference numerals are used for identical or similar components throughout the specification.

[0023] In addition, the size and thickness of each component shown in the drawing are arbitrarily shown for convenience of explanation, so the present invention is not necessarily limited to what is shown.

[0024] The present invention described below can be implemented by a design system utilizing a computer and a communication device. The communication device includes both wired and wireless communication devices.

[0025] The design system may include a malfunction consideration requirement application judgment unit, a single-fault requirement application judgment unit, an online maintenance requirement application judgment unit, a reliability improvement requirement application judgment unit, a self-diversity implementation requirement application judgment unit, a channel number reduction requirement application judgment unit, and a heterogeneous device type minimization requirement application judgment unit. In addition, the design system may include an input unit that accepts input for determining whether to apply, a design unit that designs a protection system by reflecting the application results, and an output unit that outputs the design results.

[0026] The present invention relates to a design method of a nuclear reactor protection system for individual status signals, and the individual status signals may be, but are not limited to, temperature, pressure, flow rate, or output change rate of a reactor.

[0027] The reactor protection system receives individual status signals and determines the conditions for reactor shutdown or safety device operation, and the nuclear power plant executes reactor shutdown or safety device operation based on this determination.

[0028] The reactor protection system has a basic number of channels for the above input and judgment. Each channel includes comparison logic and simultaneous logic. The comparison logic receives variable input, compares it with fixed / variable setpoints, and generates an initiation signal if the setpoints are violated. The initiation signals perform a voting function by receiving inputs from each channel in the simultaneous logic circuit (e.g., 1 out of 2, 1 out of 3, 2 out of 3, 2 out of 4), and performs different voting depending on the relevant multi-design. The following description will exemplify a case where the basic number is 1, but the present invention is not limited thereto.

[0029] A design method of a nuclear reactor protection system according to the present invention is described with reference to FIGS. 1 to 5g.

[0030] FIG. 1 is a part of a flowchart showing a design method of a nuclear reactor protection system according to an embodiment of the present invention, FIG. 2 is a flowchart showing a case where malfunction is not considered in a design method of a nuclear reactor protection system according to an embodiment of the present invention, FIGS. 3a to 3g show design results of each nuclear reactor protection system shown in FIG. 2, FIG. 4 is a flowchart showing a case where malfunction is considered in a design method of a nuclear reactor protection system according to an embodiment of the present invention, and FIGS. 5a to 5g show design results of each nuclear reactor protection system shown in FIG. 4.

[0031] First, the application of the spurious actuation requirement is determined (S10). Considering the spurious actuation requirement, i.e., to ensure that the reactor protection system maintains its functionality even in the event of a spurious actuation, the number of channels (N) increases by 1 to 2. If the spurious actuation requirement is not considered, the number of channels (N) remains at 1.

[0032] Referring to FIGS. 2 and 3a to 3g, a design method in the case where malfunction requirements are not applied is described.

[0033] First, decide whether to apply the single failure requirement (S20).

[0034] Single failure requirement refers to the requirement that the system performs its required function without any problem even if a single (1) failure occurs.

[0035] When applying the single fault requirement, the number of channels (N) increases by 1 to 2.

[0036] Next, determine whether to apply the online maintenance bypass requirement (S211, S213).

[0037] When applying the online maintenance requirement, the number of channels (N) increases by 1. Therefore, when applying both the single-failure requirement and the online maintenance requirement, the number of channels (N) becomes 3, and when applying only the single-failure requirement, the number of channels (N) becomes 2.

[0038] Next, decide whether to apply the reliability improvement requirements (S212, S214, S217).

[0039] When applying reliability enhancement requirements, each channel is multiplexed.

[0040] Finally, decide whether to apply the self-diversity implementation requirements (S215, S216, S218).

[0041] Applying the self-diversity implementation requirement requires the use of two or more logic circuits that do not fail due to the same cause. In other words, heterogeneous devices are introduced. The heterogeneous devices include, but are not limited to, PLCs, FPGAs, DCSs, and analog electronic cards.

[0042] The protection system designed according to the selection of application requirements as described above is as shown in Figs. 3a to 3g. Logic circuits with different shapes in Figs. 3a to 3g represent heterogeneous devices.

[0043] The number of channels (N) is determined based on whether malfunction consideration requirements, single-fault requirements, and online maintenance requirements are applied. Channel multiplexing is determined based on whether reliability enhancement requirements are applied. Design 1 of Fig. 3a, Design 2 of Fig. 3b, Design 6 of Fig. 3f, and Design 7 of Fig. 3g are designs to which channel multiplexing requirements are applied, while Design 3 of Fig. 3c, Design 4 of Fig. 3d, and Design 5 of Fig. 3e are designs to which channel multiplexing requirements are not applied.

[0044] Additionally, the application of heterogeneous devices to a channel varies depending on whether the self-diversity implementation requirement is applied. Designs 1, 2, 4, and 6 apply the self-diversity implementation requirement. Design 1 applies the self-diversity implementation requirement between channels, while Design 2 applies the self-diversity implementation requirement within a channel.

[0045] Next, a design method for applying malfunction requirements will be described with reference to FIGS. 4 and 5a to 5g.

[0046] As before, the number of channels (N) is determined by determining whether the single failure requirement (S30) and the online maintenance requirement (S31) are applied.

[0047] When both the single-fault requirement and the online maintenance requirement are applied, the number of channels (N) becomes 4. The increase in the number of channels due to the application of the malfunction consideration requirement, the single-fault requirement, and the online maintenance requirement is performed independently of each other.

[0048] Next, it is determined whether the reliability improvement requirements are applied (S311) and whether the self-diversity implementation requirements are applied (S312, S313).

[0049] Applying reliability enhancement requirements multiplexes each channel, and applying self-diversity implementation requirements introduces heterogeneous devices.

[0050] Next, for cases where 4 channels, multiplexing, and introduction of heterogeneous devices are applied, it is determined whether the requirement for reducing the number of channels is applied (S314).

[0051] The requirement to reduce the number of channels can also be expressed as a requirement for technology optimization.

[0052] When the channel count reduction requirement is applied, the number of channels is reduced from 4 to 3. This reduction can be performed if a channel of one type is bypassed and the single-failure requirement is satisfied by a channel of another type.

[0053] Next, decide whether to apply the requirement to minimize the number of different types of devices (S315).

[0054] The requirement to minimize heterogeneous device types can also be expressed as an economic requirement. When designing signal / function diversity, redundancy can be applied in increments of (-1). This is because when one device type is bypassed due to a failure or maintenance, the single failure criterion can be satisfied by another device type. In other words, when device 1 (N+1=3) consisting of heterogeneous devices performs online maintenance (3-1=>2, so only for a short test and maintenance time), device 2 ((N+1 = 3) consisting of heterogeneous devices) can satisfy the single failure criterion.

[0055] This enables optimized design without affecting regulatory requirements (single failure criteria / online maintenance) or safety.

[0056] When the heterogeneous device type minimization requirement is applied, the number of heterogeneous device types is reduced, for example, to two.

[0057] The application of each requirement described above can be determined by taking into consideration licensing requirements, design requirements, safety requirements, and cost.

[0058] The protection system designed according to the selection of application requirements as described above is as shown in Figs. 5a to 5g. Logic circuits with different shapes in Figs. 5a to 5g represent heterogeneous devices.

[0059] The number of channels (N) is determined by the application of malfunction considerations, single-fault requirements, and online maintenance requirements. The application of reliability enhancement requirements determines channel multiplexing, and the application of heterogeneous devices to a channel depends on the application of self-diversity implementation requirements.

[0060] Design 11 of Figure 5d is a design that incorporates all of the following requirements: malfunction consideration, single-fault tolerance, online maintenance, reliability enhancement, and self-diversity implementation. It features four channels, each with redundancy, and four different types of heterogeneous devices per channel.

[0061] When the requirement for reducing the number of channels in Design 11 is applied, the number of channels is reduced to three, as in Design 12 of Fig. 5e and Design 14 of Fig. 5g. When the requirement for minimizing the number of heterogeneous devices in Design 11 is applied, only two heterogeneous devices are used, as in Design 12 of Fig. 5e and Design 13 of Fig. 5f.

[0062] The above-described examples serve as illustrative examples of the present invention and are not intended to limit the scope of the present invention. Those skilled in the art will readily appreciate the potential for various modifications and implementations of the present invention. Therefore, the technical scope of the present invention should be defined by the appended claims.

Claims

1. In the design method of a nuclear reactor protection system for individual status signals, The above reactor protection system receives the above individual status signals and determines the reactor shutdown or safety device operation conditions. The above reactor protection system has a basic number of channels for input and judgment, A step of designing the number of channels depending on whether at least one of malfunction consideration requirement, single failure requirement and online maintenance requirement is applied; A step of designing multiplexing of the above channels depending on whether reliability enhancement requirements are applied; and A design method including a step of designing application of heterogeneous devices to the above channel depending on whether or not self-diversity implementation requirements are applied.

2. In paragraph 1, The above basic number is 1, Each of the above channels contains comparative logic and simultaneous logic, In the step of designing the number of the above channels, If malfunction considerations are applied, the number of channels is increased, If a single failure requirement is applied, the number of channels is increased, A design method that increases the number of channels when online maintenance requirements are applied.

3. In paragraph 2, A design method in which the increase in the number of channels due to application of the above malfunction consideration requirements, single failure requirements and online maintenance requirements are performed independently of each other.

4. In paragraph 3, A design method in which the number of channels increases by 1 each by applying the above malfunction consideration requirements, single failure requirements, and online maintenance requirements.

5. In paragraph 2, A design method in which multiplexing of the above channels is performed within individual channels.

6. In paragraph 5, The application of the above heterogeneous devices is It is applied in a multiplexed state of individual channels, A design method that applies to at least one of inter-channel and intra-channel.

7. In paragraph 6, With all the requirements for considering malfunctions, single-fault requirements, online maintenance requirements, reliability enhancement requirements, and self-diversity implementation requirements applied, It further includes a step of adjusting the number of channels depending on whether the requirement for reducing the number of channels is applied. The above-mentioned adjustment of the number of channels is a design method performed when a channel of one type is bypassed and a single-fault requirement is satisfied by a channel of another type.

8. In paragraph 7, A design method in which the number of channels is reduced from four to three when the above channel number reduction requirement is applied.

9. In paragraph 7, After adjusting the number of channels above, A design method further comprising a step of determining the number of types of heterogeneous devices depending on whether the requirement for minimizing the types of the heterogeneous devices is applied.

10. In paragraph 9, A design method in which the number of types of the above heterogeneous devices becomes two when the requirement for minimizing the types of the above heterogeneous devices is applied.

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